The present invention relates to methods of producing syndiotactic polypropylene articles through high performance nucleation via the presence of certain novel nucleating agents within molten syndiotactic resins, and subsequently permitting the resultant molten mixture to cool into a selected shape or configuration. Such novel nucleating agents are new classes of hyper-nucleators that promote crystallization within such target syndiotactic resins at levels well above any previously disclosed nucleators. This invention thus also encompasses the articles and compositions of such nucleated syndiotactic polypropylene as well.

The present invention relates to methods of producing syndiotactic polypropylene (s-PP) articles through high performance nucleation via the presence of certain novel nucleating agents within molten syndiotactic resins, and subsequently permitting the resultant molten mixture to cool into a selected shape or configuration. Such novel nucleating agents are a new class of nucleators that promote crystallization within such target syndiotactic resins at levels well above any previously disclosed nucleators. This invention thus also encompasses the articles and compositions of such syndiotactic polypropylene as well.
All U.S. patents cited below are herein entirely incorporated by reference.
Polypropylene has long been known to exist in several forms. Generally, isotactic propylene (iPP) can be described as having the methyl groups attached to the tertiary carbon atoms of successive monomeric units on the same side of a hypothetical plane through the polymer chain, whereas syndiotactic polypropylene (sPP) may generally be described as having the methyl groups attached on alternating sides of the polymer chain. More specifically, the isotactic structure is typically described as having the methyl groups attached to the tertiary carbon atoms of successive monomeric units on the same side of a hypothetical plane through the main chain of the polymer, e.g., the methyl groups are all above or all below the plane. A more thorough description of syndiotactic polypropylene is found in col. 1, line 19 of col. 3 of U.S. Pat. No. 5,969,021 to Reddy et al., particularly in comparison with the general configurations of isotactic polypropylene. Thus, syndiotactic polymers, in contrast to the isotactic structure, are those in which the methyl groups attached to the tertiary carbon atoms of successive monomeric units in the chain lie on alternate sides of the plane of the polymer, thereby creating a configuration of successive methyl groups on alternate sides of a common plane (i.e., racemic dyads). The percentage of racemic dyads in the chain thus determines the degree of syndiotacticity of the polymer. Syndiotactic polymers are crystalline and, like the isotactic polymers, are insoluble in xylene (although the degree of crystallinity of s-PP is much less than for i-PP). This crystallinity distinguishes both syndiotactic and isotactic polymers from an atactic polymer which is amorphous, and soluble in xylene. Atactic polypropylene exhibits no regular order of repeating unit configurations in the polymer chain and forms essentially a waxy product. Furthermore, s-PP exhibits a far lower melting point (xcx9c128xc2x0 C.) than for i-PP (xcx9c153-170xc2x0 C.).
Such noticeable physical differences in comparison with i-PP allow for utility of s-PP in specialized applications. For example, syndiotactic polypropylene provides such improved characteristics over isotactic types, namely, but not limited to, clarity, toughness (impact resistance), and feel (softness), as well as surface smoothness and uniformity, some improvements to an extraordinary degree. Thus, end-uses such as dental retainers, medicine droppers, eye droppers, and pen caps normally include s-PP as the primary polymer. However, historic utilization of such a polymer within other fields has been severely limited due to problems associated with low crystallization rates and crystallization temperatures (and thus inordinate cost levels), as well as low flexural modulus characteristics.
As noted within the citation to Reddy et al., above, the crystallization rate of syndiotactic polypropylene is much slower than that for isotactic PP due the low retention rate of crystallinity exhibited by syndiotactic polypropylene in general. In fact, syndiotactic polypropylene continues to crystallize even after pelletization thereof during the production of the resin throughout the process. Furthermore, such low crystallization temperatures also require cooling of injection molded parts or extruded films or sheets to much lower temperatures, and in some cases, higher than needed, for example, for isotactic polypropylene, thereby adding to the cost of manufacture as well due to slower production rates and increased energy costs. Additionally, not only does syndiotactic polypropylene have crystallization temperatures and rates that could be improved, some common processing additives, such as calcium stearate, tend to reduce the crystallization rate even more.
Such slow crystallization rates are generally attributable to the fact that syndiotactic polypropylenes exhibit polymorphism; that is, three different crystal types, namely cell I, cell II, and cell III structures therein. Due to the inherent similarities between Cell I and Cell III, only Cell III will be referred to hereinafter. It has been traditionally noted that the manufacture of syndiotactic polypropylene requires two distinct steps after melting of the target resin in order for the crystal structures to change from one structure to another and finally to the desired final type (cell II). The initial crystal configuration, known as cell II (which includes anti-chiral helices along the xe2x80x9caxe2x80x9d crystallographic axis and chiral helices along the xe2x80x9cbxe2x80x9d axis), appears quickly during cooling and is kinetically favored. The cell III crystal structure (which includes anti-chiral helices along both the xe2x80x9caxe2x80x9d and xe2x80x9cbxe2x80x9d crystallographic axes) then forms at relatively high temperatures (thermodynamically favored) during cooling of the molten resin form. Such a cell III structure for syndiotactic polypropylene (higher melting), although formed more slowly, is always in competition with the Cell II form (lower melting), and is not desirable since it is a rubbery, opaque phase and cannot be pelletized during processing. In order to effectuate proper cell II formation, generally such rubbery cell III-type s-PP must then, in general non-limiting terms, be extruded into strands and wound around a spool to permit further cooling and thus generation of the necessary rigidifying cell II configuration. Thus, it appears that the crystallization rate of syndiotactic polypropylene is dictated by the amount of cell III crystals present and thus requiring generation and arrangement within the target polymer. Without intending on being limited to any scientific theory, it appears that proper and useful syndiotactic polypropylene articles should include higher amounts of the rigid cell II crystal types. The apparent problem in the past with slow crystallization procedures lies in the presence of large amounts of cell III crystals therein. A lower amount of such cell III crystal types would thus permit more thorough crystallization of the overall syndiotactic polypropylene during the initially formed cell II phase, thereby reducing the amount of time required for full crystallization thereof. As a result, it is believed that a syndiotactic polypropylene production method that generates higher amounts of cell II crystal structures than cell III types would exhibit faster crystallization (or at least higher crystallization temperatures) and thus would reduce the cost and complexity associated with producing syndiotactic polypropylene articles. In effect, then, such an improved method would permit more widepread use of such an excellent performing class of polypropylenes. As it is today, the dichotomy in melting forms between cell II and III crystal structures causes a processing problem in terms of complexity and time and thus such syndiotactic polypropylene types have proven very difficult to efficiently produce, even with certain nucleating agents present. Thus, as noted above, the need appears to be to reduce the amount of cell III present therein, thus permitting the cell II component to dictate polymer formation, preferably wherein more cell II form is produced than cell III crystals. Furthermore, it appears that a reduction in the amount of rubbery cell III crystals within target s-PP formulations leads to the formation of more flexurally stable end-product articles as well (e.g., the fewer rigid cell II crystals are present, the polypropylene tends to be more flexible and less susceptible to breaking). Unfortunately, to date no such specific advancement has been proffered to the syndiotactic polypropylene industry wherein the majority of s-PP crystals are Cell II.
Thus, in spite of the advancements in the prior art relating to syndiotactic polypropylene, there is a need for a method of improving the crystallization rate and temperature of syndiotactic polypropylene, in addition to the stiffness of final s-PP articles. As a result, then, there is also a need in the art for improving such characteristics, particularly in order to allow for utility of s-PP within larger market areas, particularly those which are today dominated by isotactic polypropylene. To date, no such advancements have been made available increasing the crystallization rates of syndiotactic polypropylene to levels acceptable to displace isotactic polypropylene as the base polymer in certain end-uses.
It is an object of the present invention to provide for a method of improving the crystallization rate and temperature of syndiotactic polypropylene. It is another object of the present invention to provide for a syndiotactic polypropylene having improved crystallization rate and temperature of syndiotactic polypropylene. It is even another object of the present invention to provide for products made from syndiotactic polypropylene having improved crystallization rate and temperature of syndiotactic polypropylene.
Accordingly, this invention encompasses a method of treating syndiotactic polypropylene comprising the step of compounding syndiotactic polypropylene with at least one compound selected from the group consisting of compounds conforming with either of formulae (I) or (II)
wherein M1 and M2 are the same or different or are combined to form a single moiety and are selected from at least one metal cation (such as, without limitation, sodium, potassium, calcium, strontium, lithium, and monobasic aluminum), and wherein R1, R2, R3, R4, R5, R6, R7, R8, R9, and R10 are either the same or different and are individually selected from the group consisting of hydrogen, C1-C9 alkyl [wherein any two vicinal (neighboring) or geminal (same carbon) alkyl groups may be combined to form a carbocyclic ring of up to six carbon atoms], hydroxy, C1-C9 alkoxy, C1-C9 alkyleneoxy, amine, and C1-C9 alkylamine, halogens (fluorine, chlorine, bromine, and iodine), and phenyl, wherein geminal constituents may be the same except that such geminal constituents cannot simultaneously be hydroxy; and wherein geminal constituents may be different from each other, except that such geminal constituents may not be hydroxy and halogen or hydroxy and amine simultaneously;
wherein R11, R12, R13, R14, R15, R16, R17, R18, R19, and R20 group consisting of hydrogen, C1-C9 alkyl, hydroxy, C1-C9 alkoxy, C1-C9 alkyleneoxy, amine, and C1-C9 alkylamine, halogen, phenyl, alkylphenyl, and geminal or vicinal C1-C9 carbocyclic, wherein geminal constituents may be the same except that such geminal constituents cannot simultaneously be hydroxy; and wherein geminal constituents may be different from each other, except that such geminal constituents may not be hydroxy and halogen or hydroxy and amine simultaneously; wherein Rxe2x80x2 and Rxe2x80x3 are the same or different and are individually selected from the group consisting of hydrogen, C1-C30 alkyl, hydroxy, amine, polyoxyamine, C1-C30 alkylamine, phenyl, halogen, C1-C30 alkoxy, C1-C30 polyoxyalkyl, C(O)xe2x80x94NR21C(O), and C(O)Oxe2x80x94Rxe2x80x2xe2x80x3, wherein R2 is selected from the group consisting of C1-C30 alkyl, hydrogen, C1-C30 alkoxy, and C1-C30 polyoxyalkyl, and wherein Rxe2x80x2xe2x80x3 alone or two adjacent Rxe2x80x2xe2x80x3 groups (such as when Rxe2x80x2 and Rxe2x80x3 are the same) are combined to from a single moiety which is selected from the group consisting of hydrogen, a metal ion (such as, without limitation, sodium, potassium, calcium, strontium, lithium, and monobasic aluminum), an organic cation (such as quaternary amines), polyoxy-C2-C18-alkylene, C1-C30 alkyl, C1-C30 alkylene, C1-C30 alkyleneoxy, a steroid moiety, phenyl, polyphenyl, C1-C30 alkylhalide, and C1-C30 alkylamine; and wherein at least one of Rxe2x80x2 and Rxe2x80x3 is either C(O)xe2x80x94NR21C(O) or C(O)Oxe2x80x94Rxe2x80x2xe2x80x3. The term xe2x80x9cmonobasic aluminumxe2x80x9d is well known and is intended to encompass an aluminum hydroxide group as a single cation bonded with the two carboxylic acid moieties. Furthermore, for Formula I, in each of these potential compounds, the stereochemistry at the metal carboxylates may be cis or trans, although cis is preferred. In Formula II, the stereochemistry at the Rxe2x80x2 and Rxe2x80x3 groups may be cis-exo, cis-endo, or trans, although cis-endo is preferred.
According to still another potential embodiment of the present invention, there is provided a method of forming a product including the step of heating a mixture comprising syndiotactic polypropylene and an additive above the melt temperature of the syndiotactic polypropylene to form a melted mixture, wherein the additive comprises at least one selected from the group consisting of compounds of either Formula (I) or (II), or mixtures thereof. The method also includes the step of forming the melted mixture into a desired shape, particularly a method wherein the shaped article is formed by cooling the desired shape to below the melt temperature of the syndiotactic polypropylene.
Further encompassed within this invention is a syndiotactic polypropylene article (wherein the definition of syndiotactic polypropylene can include the presence of up to about 30 weight percent isotactic, atactic, or mixtures thereof, polypropylene types), exhibiting a peak crystallization temperature (peak Tc) of at least 71xc2x0 C., preferably at least about 74xc2x0 C., when measured via differential scanning calorimetry (DSC) under a modified version of ASTM Test Method D-794-85, wherein the sample is cooled at a rate of 20xc2x0 C. per minute, or alternatively, exhibits the same high peak crystallization temperature as well as a flexural modulus of at least 900 MPa as determined according to ASTM Test Method ASTM D790-98, procedure B. Lastly, this invention also encompasses a syndiotactic polypropylene that exhibits a greater amount of cell II crystal structures in comparison with cell III crystal structures within the same final polymer product, as measured via DSC analysis.
As noted above, in order to develop a proper high crystallizing syndiotactic propylene to permit widespread commercial applications of such a unique polymer, a novel nucleating technology was developed that unexpectedly produces a range of amounts of cell II (lower melting) crystal formations from a slight excess to much greater levels in comparison with the amount produced of the cell III (higher melting) types. Surprisingly, such novel nucleators as noted below not only generated such greater amounts of higher cell II crystal structures, they also provided higher, and in some cases, extremely higher crystallization temperatures for target syndiotactic polypropylenes. As a result, efficiency has been increased and complexity has been reduced in relation to unnucleated syndiotactic polypropylene during processing. Also, such novel nucleators are compatible with common syndiotactic polypropylene additives.
Such inventive nucleating procedures thus encompass the addition of certain types of bicyclic or monocylic dicarboxylic acid salts or mono-salts (half-acid, half salt) compounds, noted above in terms of Formulae (I) or (II). The non-limiting preferred type of nucleating additive is a monocyclic diacid salt (such as cis-calcium hexahydrophthalate) that induces a peak crystallization temperature in excess of 74xc2x0 C. for syndiotactic polypropylene containing about 70-80% racemic dyads. As noted below within the examples, such a high crystallizing nucleating procedure is a highly unexpected improvement over the standard procedures utilizing NA-11 as the standard nucleator. With the cost of such polypropylene already quite high. (due to its manufacture via expensive metallocene catalysis), the utilization of such syndiotactic types have been avoided. The ability now to increase the efficiency of processing of such a specific polypropylene thus translates into not only lower costs to the consumer, but also the ability to potentially enter markets previously unavailable to such excellent polypropylene formulations and articles.
The syndiotactic polypropylene utilized in the present invention, and methods of making such a syndiotactic polypropylene, are well known to those of skill in the polyolefin arts. An example of a suitable syndiotactic polypropylene and a method of its making can be found in U.S. Pat. No. Nos. 4,892,851, 5,334,677, and 5,476,914, all herein entirely incorporated by reference.
Preferably, the syndiotactic polypropylene utilized in the present invention comprises tacticity of at least 70 percent racemic dyad molecules as defined by the percent of racemic dyads (i.e., an amount of isotactic or other type of non-syndiotactic polypropylene of at most about 30 weight percent). It is foreseen that desired syndiotactic polypropylene utilizing the inventive nucleation techniques will comprise syndiotacticity of at least 80 percent racemic dyads, even more preferably at least 83 percent racemic dyads, and still more preferably at least about 90 percent racemic dyads. Most preferably, such foreseen syndiotactic polypropylenes utilizing the present inventive nucleation techniques would consist of all syndiotactic molecules.
The syndiotactic polypropylene useful in the present invention will generally be selected according to the desired end use of polypropylene, for compatibility with the additives, and for compatibility with the processing conditions, and with any other polymers to be added thereto.
As a non-limiting example, a suitable syndiotactic polypropylene which may be utilized in the present invention may generally be described as having a number average molecular weight in the range of about 30000 to about 150000, a weight average molecular weight in the range of about 60000 to 350000, a melting point in the range of about 95xc2x0 C. to about 165xc2x0 C., a bulk density in the range of about 0.28 to about 0.55 g/cc, polymer density in the range of about 0.87 to 0.90 g/cc, polydispersity in the range of about 2 to about 5, and a percent racemic dyad value between about 70-74 percent.
The particular compounds noted above, as proper nucleating agents present within such syndiotactic polypropylenes include any compound encompassed within the Formulae of (I) or (II), as defined above in detail. Preferably, for Formula (I), all of the R groups are hydrogen and the M groups are combined to form a calcium ion. For Formula (II), all the R groups, except Rxe2x80x2 and Rxe2x80x3, are hydrogens, and both Rxe2x80x2 and Rxe2x80x3 are carboxylic acids with the Rxe2x80x2xe2x80x3 groups individual sodium ions.
Such aforementioned nucleation properties within syndiotactic polypropylene are highly unexpected and unpredictable, particularly in view of the closest prior art, namely within U.S. Pat. No. 3,207,739 to Wales, as well as within Beck, H. N., xe2x80x9cHeterogeneous Nucleating Agents for Polypropylene Crystallization,xe2x80x9d Journal of Applied Polymer Science, Vol. 11, pp. 673-685 (1967), which disclose disodium hexahydrophthalate as a possible, though not preferred, nucleator for polymers (such disclosures are directed more specifically to sodium benzoate and other like aromatic compounds as better nucleators), and WO 98/29494 which discloses nucleation and clarification additives for polyolefin articles including unsaturated [2.2.1] dicarboxylate salts; however, there is no exemplification of a saturated dicarboxylate (or similar saturated structure) of this type (other than heterocyclic camphanic acid). The closest embodiment within that art is identified as disodium bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate. None of these references discuss any nucleation advantages for the taught compounds in relation specifically to syndiotactic polypropylene to the degree herein realized. Most notably, the utilization of such compounds as noted above provide highly unexpected improvements in crystallization rates and temperatures, as well as stiffness and, perhaps, most importantly, the amount of cell II crystals formed within the target polymer in relation to the amount of cell III crystals therein. Again, the aforementioned prior art references fail to provide any motivation for the introduction of such compounds as encompassed within Formulae (I) and/or (II), above, within syndiotactic polypropylene. Thus, after intensive investigations, it has been determined that, quite unexpectedly, as discussed below in greater detail, the utilization of certain preferred, and non-limiting, metal hexahydrophthalates, and, to a lesser extent, the utilization of nucleating compounds produced through the hydrogenation of unsaturated bicyclic carboxylic acid salts, provide vastly improved nucleation results for syndiotactic polypropylenes to a level heretofore unattainable, particularly at a commercially viable level. As indicated in Table I, below, as one example of this phenomenon, the peak crystallization temperatures provided the inventive syndiotactic polyolefin articles are from about 1 to as high as about 6xc2x0 C. above that for the standard, previously best performing syndiotactic nucleator compounds. Such dramatic improvements are simply unexpected and are unpredictable from any known empirical or theoretical considerations and are of great practical significance as discussed before.
As noted above, proper nucleator compounds for industrial applications require a number of important criteria to be met, such as shelf stability, particularly in terms of low hygroscopicity, high final article stiffness, gas barrier properties, and plastic additive compatibility, such as stability in combination with acid scavengers, such as calcium stearate, for example. The compounds noted above in Formulae (I) and (II) appear to meet all of these important requirements very well. For instance, these inventive compounds do not hydrate readily and thus granular or powder formulations of such a salt do not agglomerate or clump together. The cost benefits from such shelf stability are apparent since there is little if any need to separate agglomerated powders upon introduction to thermoplastic processing equipment. Additionally, such nucleating salts provide high stiffness (modulus) characteristics to the overall final syndiotactic polyolefin product without the need for extra fillers and reinforcing agents, although such potentially unnecessary additives may be added if such are desired to improve the target properties therein. Lastly, and of great importance within the polypropylene industry, such inventive salts do not react deleteriously with calcium stearate co-additives. Such a property, combined with the other attributes, is highly unexpected and unpredictable.
The HHPA and/or bicyclic salts of Formula (I) and/or (II), above, are thus added within the target syndiotactic polypropylene in an amount from about 0.01 percent to 5.0 percent by weight, more preferably from about 0.02 to about 3.0 percent, and most preferably from about 0.05 to 2.5 percent, in order to provide the aforementioned beneficial characteristics (1.0% by weight equals about 10,000 ppm). It may also be desirable to include up to 50% or more of the active compound in a masterbatch, although this is not a restriction. Optional additives within the nucleating salt-containing composition, or within the final thermoplastic article made therewith, may include plasticizers, stabilizers, ultraviolet absorbers, and other similar standard thermoplastic additives. Other additives may also be present within this composition, most notably antioxidants, antimicrobial agents (such as silver-based compounds, preferably ion-exchange compounds such as ALPHASAN(copyright) antimicrobials from Milliken and Company), antistatic compounds, perfumes, chloride scavengers, and the like. These coadditives, along with the nucleating agents, may be present as an admixture in powder, liquid, or in compressed/pelletized form for easy feeding. The use of dispersing aids may be desirable, such as polyolefin (e.g., polyethylene) waxes, stearate esters of glycerin, montan waxes, and mineral oil. Basically, the nucleating compounds may be present (up to 20% by weight or more) in any type of standard additive form, including, without limitation, powder, prill, agglomerate, liquid suspension, and the like, particularly comprising the dispersing aids described above. Compositions made from blending, agglomeration, compaction, and/or extrusion may also be desirable.
Non-limiting commercially available products suitable for use in the practice of the present invention, in addition to the inventive nucleators noted above, include Millad(copyright) 3988 (3,4-dimethyldibenzylidene sorbitol), available from Milliken Chemical, NA-11(copyright) (sodium 2,2-methylene-bis-(4,6, di-tert-butylphenyl)phosphate))), available from Asahi Denka Kogyo, and aluminum bis[2,2xe2x80x2-methylene-bis-(4,6-di-tert-butylphenyl)phosphate], which is hereinafter referred NA-21(copyright), also available from Asahi Denka Kogyo.
The crystallization additive or additives may be added to the syndiotactic polypropylene during or after polymerization. Preferably, it is added to the syndiotactic polypropylene as it is being extruded through the extrusion die.
In the present invention, the syndiotactic polypropylene treated with the crystallization additive, will have a peak crystallization temperature that is improved as compared to the untreated syndiotactic polypropylene. Generally, the peak crystallization temperature of the treated syndiotactic polypropylene is in excess of about 71xc2x0 C. (for syndiotactic polypropylene comprising about 70-75% syndiotacticity), preferably in excess of about 74xc2x0 C. (for syndiotactic polypropylene comprising about 70-75% syndiotacticity), most preferably in excess of about 77xc2x0 C. (by DSC analysis when a cooling rate of 20xc2x0 C./minute is used).
The syndiotactic polypropylene crystallized according to the present invention will also have an increased content of cell II (low melting form) structure and a decreased content of cell III (high melting form) such that the amount of cell II at least about the same in amount as that of cell III (such as low as about 45% cell II correlated to about 55% cell III, although higher amounts of cell II are more highly desired for crystallization and manufacturing speed improvements).
Non-limiting examples of possible reinforcing agents which may be added to the target syndiotactic polypropylene include inorganic or organic products of high molecular weight, including glass fiber, asbestos, boron fibers, carbon and graphite fibers, whiskers, quartz and silica fibers, nanocomposites (such as Montmorillonite clays), and synthetic organic fibers. When such conventional ingredients are utilized, they will generally be present in a range from about 0.01 to about 50 weight percent of the blend, preferably in a range from about 1 to about 25 weight percent of the blend.
The following Examples are provided merely to illustrate selected embodiments of the present invention and do not limit the scope of the claims.
Production of Inventive Salts
To an 8-L cylindrical kettle fitted with a mechanical paddle stirrer and thermometer was added water (4 L) and calcium hydroxide (481 g, 6.49 moles) with stirring at room temperature. To this slurry was added cis-hexahydrophthalic anhydride (1 kg, 6.49 moles) and the slurry was heated to 50xc2x0 C. After stirring with heat for 5 hours, the mixture became quite thick, at which time the pH of the aqueous phase was found to be about 7. The white product was collected by suction filtration, washed with copious amounts of water, dried in a vacuum oven overnight at 140xc2x0 C., and further air-jet milled to provide a powder of roughly uniform particle sizes. The dry weight was 1270 grams (93% yield) having a melting point greater than about 400xc2x0 C. The IR spectrum was consistent with that of the expected product.
To a solution of disodium bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate (10.0 g) in water (100 g) was added 0.5 g palladium on activated carbon (5 wt%). The mixture was transferred into a Parr reactor and was subjected to hydrogenation (50 psi, room temperature) for 8 hours. The activated carbon was filtered out, and the water was removed in vacuo at 75xc2x0 C. The resulting product (m.p  greater than 300xc2x0 C.) was dried and milled. NMR and IR analyses were consistent with that of the expected structure.
Base Polymers
The base s-PP fluff used for compounding had a racemic dyad content of between 70 and 80% and a MFR of about 4 g/10 min., and was unstabilized as received. For stabilization, it was compounded with an antioxidant package containing 500 ppm Irganox(copyright) 1010 (Ciba Geigy) {tetrakis-(methylene[3,5-di-tert-butyl-4-hydroxyhydrocinnamate]methane)} and 1000 ppm Irgafos(copyright) 168 (Ciba Geigy), plus the individual nucleating agents, either inventive or comparative in nature, as noted below. Calcium stearate (CaSt) was used at 800 ppm as the acid-acceptor, except in the case of NA-11 and sodium benzoate (NaBz), wherein dihydrotalcite (DHT4-A, Kyowa Chemical) was used at a level of 400 ppm. The compounded fluff was mixed thoroughly in a Welex mixer and extruded on a Prism 16 mm twin-screw microextruder into strands. The strands were cooled on a spool to room temperature and pelletized using a laboratory pelletizer. Extrusion conditions were as follows: Zone 1, 370xc2x0 F., Zone 2, 415xc2x0 F., Zone 3, 435xc2x0 F., and Zone 4 (die), 455xc2x0 F. 1 kg batches of pellets were thus made in this manner.
Testing for nucleating effects and other important criteria were accomplished through the formation of 50 mil plaques from the pelletized syndiotactic polypropylene thermoplastic resin. The plaques were molded on an Arburg (20 ton) press using a barrel temperature of 205xc2x0 C. and a mold temperature held at 100xc2x0 F. It was observed that for the unnucleated control resin, the plaque crystallization was characterized by a hazy, rubbery phase which gradually transformed into a clear, rigid phase. The minimum cycle time for these plaques was thus determined to be the minimum time required to eject a transparent plaque without warpage of the part on further cooling. These plaques were formed through the process outlined above with the specific nucleating agents listed in the Table below.
These plaque formulations are, of course, merely preferred embodiments of the inventive article and method and are not intended to limit the scope of this invention. The resultant plaques were also tested for peak crystallization temperatures (by Differential Scanning Calorimetry, or DSC) with a 20xc2x0 C./min. cooling rate. Generally, a polyolefin such as unnucleated syndiotactic polypropylene has a peak crystallization temperature of about 60-70xc2x0 C. at most on cooling when comprised of about 70-80% racemic dyads and when measured at a DSC cooling rate of 20xc2x0 C./min. In order to reduce the amount of time needed to form the final product, as well as to provide the most effective nucleation for the polyolefin, the best nucleator compound added will invariably also provide the highest crystallization temperature for the final syndiotactic PP product. The nucleation composition efficacy, particular polymer onset and peak crystallization temperature (Tc), was evaluated by using DSC according to ASTM D-794-85. To measure these temperatures, the specific syndiotactic polypropylene compositions listed below were heated from 25xc2x0 C. to 220xc2x0 C. at a rate of 20xc2x0 C. per minute to produce a molten formulation and held at the peak temperature for 2 minutes. At that time, the temperature was then lowered at a rate of 20xc2x0 C. per minute until it reached the starting temperature of 25xc2x0 C. The crystallization temperature was thus measured as the peak maximum during the crystallization exotherm. The clarification performance of the nucleators was measured using ASTM D 1003-92. The stiffness of each sample was measured in accordance with ASTM D790-98, procedure B.
Table 1 below lists the onset and peak crystallization temperatures, haze measurements, and flexural modulus results for the plaques prepared above:
The data shows that the inventive nucleators, and thus the inventive syndiotactic propylene, exhibit significantly higher polymer onset and peak crystallization temperatures and flexural modulus measurements than for the comparative nucleators. In addition, the clarity of the compositions is not drastically affected when Example 1 and 2 are used in the formulation.
To determine the relative amounts of Cell II and Cell III crystal structures within each tested formulation, the first melting transitions were observed after injection molding. The Cell II form melts at about 115xc2x0 C., while the Cell III form melts at about 126xc2x0 C. on heating at 20xc2x0 C./minute. The combined DSC thermograms are shown FIG. 1.

Highly nucleated syndiotactic polypropylene


The present invention relates to Human Ckxcex2-9 polypeptides and DNA (RNA) encoding such chemolcine polypeptides. Moreover, a procedure for producing such polypeptides by recombinant techniques is disclosed. Also disclosed are methods for utilizing such Ckxcex2-9 polypeptides for the treatment of leukemia, tumors, chronic infections, autoimmune diseases, fibrotic disorders, wound healing and psoriasis. Antagonists against such polypeptides and their use as a therapeutic agent to treat rheumatoid arthritis, autoimmune and chronic inflammatory and infective disease, allergic reactions, prostaglandin-independent fever and bone marrow failure are also disclosed. Diagnostic assays are also disclosed which detect the presence of mutations in the Ckxcex2-9 coding sequence and over-expression of the Ckxcex2-9 protein.

This invention relates to newly identified polynucleotides, polypeptides encoded by such polynucleotides, the use of such polynucleotides and polypeptides, as well as the production of such polynucleotides and polypeptides. More particularly, the polypeptides of the present invention are human chemokine beta-9 sometimes hereinafter referred to as xe2x80x9cCkxcex2-9xe2x80x9d. The invention also relates to inhibiting the action of such polypeptides.
Chemokines, also referred to as intercrine cytokines, are a subfamily of structurally and functionally related cytokines. These molecules are 8-10 kd in size. In general, chemokines exhibit 20% to 75% homology at the amino acid level and are characterized by four conserved cysteine residues that form two disulfide bonds. Based on the arrangement of the first two cysteine residues, chemokines have been classified into two subfamilies, alpha and beta. In the alpha subfamily, the first two cysteines are separated by one amino acid and hence are referred to as the xe2x80x9cCxe2x80x94Xxe2x80x94Cxe2x80x9d subfamily. In the beta subfamily, the two cysteines are in an adjacent position and are, therefore, referred to as the xe2x80x9cCxe2x80x94Cxe2x80x9d subfamily. Thus far, at least eight different members of this family have been identified in humans.
The intercrine cytokines exhibit a wide variety of functions. A hallmark feature is their ability to elicit chemotactic migration of distinct cell types, including monocytes, neutrophils, T lymphocytes, basophils and fibroblasts. Many chemokines have pro-inflammatory activity and are involved in multiple steps during an inflammatory reaction. These activities include stimulation of histamine release, lysosomal enzyme and leukotriene release, increased adherence of target immune cells to endothelial cells, enhanced binding of complement proteins, induced expression of granulocyte adhesion molecules and complement receptors, and respiratory burst. In addition to their involvement in inflammation, certain chemokines have been shown to exhibit other activities. For example, macrophage inflammatory protein 1 (MIP-1) is able to suppress hematopoietic stem cell proliferation, platelet factor-4 (PF-4) is a potent inhibitor of endothelial cell growth, Interleukin-3 (IL-8) promotes proliferation of keratinocytes, and GRO is an autocrine growth factor for melanoma cells.
In light of the diverse biological activities, it is not surprising that chemokines have been implicated in a number of physiological and disease conditions, including lymphocyte trafficking, wound healing, hematopoietic regulation and immunological disorders such as allergy, asthma and arthritis.
Members of the xe2x80x9cCxe2x80x94Cxe2x80x9d branch exert there effects on the following cells: eosinophils which destroy parasites to lessen parasitic infection and cause chronic inflammation in the airways of the respiratory system; macrophages which suppress tumor formation in vertebrates; and basophils which release histamine which plays a role in allergic inflammation. However, members of one branch may exert an effect on cells which are normally responsive to the other branch of chemokines and, therefore, no precise role can be attached to the members of the branches.
While members of the Cxe2x80x94C branch act predominantly on mononuclear cells and members of the Cxe2x80x94Xxe2x80x94C branch act predominantly on neutrophils a distinct chemoattractant property cannot be assigned to a chemokine based on this guideline. Some chemokines from one family show characteristics of the other.
The polypeptide of the present invention has been putatively identified as Ckxcex2-9 based on amino acid sequence homology.
In accordance with one aspect of the present invention, there are provided novel polypeptides as well as biologically active and diagnostically or therapeutically useful fragments, analogs and derivatives thereof. The polypeptide of the present invention is of human origin.
In accordance with another aspect of the present invention, there are provided isolated nucleic acid molecules encoding the polypeptide of the present invention, including mRNAs, DNAs, cDNAs, genomic DNAs as well as analogs and biologically active and diagnostically or therapeutically useful fragments and derivatives thereof.
In accordance with yet a further aspect of the present invention, there is provided a process for producing such polypeptides by recombinant techniques comprising culturing recombinant prokaryotic and/or eukaryotic host cells, containing a nucleic acid sequence encoding a polypeptide of the present invention, under conditions promoting expression of said protein and subsequent recovery of said protein.
In accordance with yet a further aspect of the present invention, there is provided a process for utilizing such polypeptides, or polynucleotides encoding such polypeptides for therapeutic purposes, for example, to treat solid tumors, chronic infections, auto-immune diseases, psoriasis, asthma, allergy, to regulate hematopoiesis, and to promote wound healing.
In accordance with yet a further aspect of the present invention, there are provided antibodies against such polypeptides.
In accordance with yet another aspect of the present invention, there are provided antagonists to such polypeptides, which may be used to inhibit the action of such polypeptides, for example, in the treatment of auto-immune diseases, chronic inflammatory diseases, histamine-mediated allergic reactions, asthma, arthritis, prostaglandin-independent fever, bone marrow failure, silicosis, sarcoidosis, hyper-eosinophilic syndrome and lung inflammation.
In accordance with yet a further aspect of the present invention, there are also provided nucleic acid probes comprising nucleic acid molecules of sufficient length to specifically hybridize to a nucleic acid sequence of the present invention.
In accordance with still another aspect of the present invention, there are provided diagnostic assays for detecting diseases related to the expression of the polypeptide and mutations in the nucleic acid sequences encoding such polypeptide.
In accordance with yet a further aspect of the present invention, there is provided a process for utilizing such polypeptides, or polynucleotides encoding such polypeptides, for in vitro purposes related to scientific research, synthesis of DNA and manufacture of DNA vectors.
These and other aspects of the present invention should be apparent to those skilled in the art from the teachings herein.
The following drawings are illustrative of embodiments of the invention and are not meant to limit the scope of the invention as encompassed by the claims.
FIG. 1 displays the cDNA sequence and corresponding deduced amino acid sequence of Ckxcex2-9. The initial 23 amino acids represent the leader sequence such that the putative mature polypeptide comprises 111 amino acids. The standard one-letter abbreviation for amino acids is used.
FIG. 2 displays the amino acid sequence homology between Ckxcex2-9 and the mature peptide of eotaxin (bottom).
In accordance with an aspect of the present invention, there are provided isolated nucleic acids (polynucleotides) which encode for the mature polypeptides having the deduced amino acid sequences of FIG. 1 (SEQ ID No. 2) or for the mature polypeptide encoded by the cDNA of the clones deposited as ATCC Deposit No. 75803 on Jun. 7, 1994.
This ATCC number is directed to a biological deposit with the ATCC, located at American Type Culture Collection, 10801 University Boulevard, Manassas. Va. 20110-2209.
The polynucleotide encoding Ckxcex2-9 was discovered in a cDNA library derived from a human breast lymph node. Ckxcex2-9 is structurally related to the chemokine family. It contains an open reading frame encoding a protein of 134 amino acid residues of which approximately the first 23 amino acids residues are the putative leader sequence such that the mature protein comprises 111 amino acids. The protein exhibits the highest degree of homology to eotaxin with 32% identity and 69% similarity over a stretch of 75 amino acid residues. It is also important that the four spatially conserved cysteine residues in chemokines are found in the polypeptides of the present invention.
The polynucleotides of the present invention may be in the form of RNA or in the form of DNA, which DNA includes cDNA, genomic DNA, and synthetic DNA. The DNA may be double-stranded or single-stranded, and if single stranded may be the coding strand or non-coding (anti-sense) strand. The coding sequence which encodes the mature polypeptides may be identical to the coding sequence shown in FIG. 1 (SEQ ID No. 1) or that of the deposited clones or may be a different coding sequence which coding sequence, as a result of the redundancy or degeneracy of the genetic code, encodes the same mature polypeptides as the DNA of FIG. 1 (SEQ ID No. 1) or the deposited cDNA.
The polynucleotides which encodes for the mature polypeptides of FIG. 1 (SEQ ID No. 2) or for the mature polypeptides encoded by the deposited cDNA may include: only the coding sequence for the mature polypeptide; the coding sequence for the mature polypeptide and additional coding sequence such as a leader or secretory sequence or a proprotein sequence; the coding sequence for the mature polypeptide (and optionally additional coding sequence) and non-coding sequence, such as introns or non-coding sequence 5xe2x80x2 and/or 3xe2x80x2 of the coding sequence for the mature polypeptides.
Thus, the term xe2x80x9cpolynucleotide encoding a polypeptidexe2x80x9d encompasses a polynucleotide which includes only coding sequence for the polypeptide as well as a polynucleotide which includes additional coding and/or non-coding sequence.
The present invention further relates to variants of the hereinabove described polynucleotides which encode for fragments, analogs and derivatives of the polypeptide having the deduced amino acid sequence of FIG. 1 (SEQ ID No. 2) or the polypeptide encoded by the cDNA of the deposited clones. The variant of the polynucleotides may be a naturally occurring allelic variant of the polynucleotides or a non-naturally occurring variant of the polynucleotides.
Thus, the present invention includes polynucleotides encoding the same mature polypeptides as shown in FIG. 1 (SEQ ID No. 2) or the same mature polypeptides encoded by the cDNA of the deposited clones as well as variants of such polynucleotides which variants encode for a fragment, derivative or analog of the polypeptides of FIG. 1 (SEQ ID No. 2) or the polypeptides encoded by the cDNA of the deposited clones. Such nucleotide variants include deletion variants, substitution variants and addition or insertion variants.
As hereinabove indicated, the polynucleotides may have a coding sequence which is a naturally occurring allelic variant of the coding sequence shown in FIG. 1 (SEQ ID No. 2) or of the coding sequence of the deposited clones. As known in the art, an allelic variant is an alternate form of a polynucleotide sequence which may have a substitution, deletion or addition of one or more nucleotides, which does not substantially alter the function of the encoded polypeptide.
The present invention also includes polynucleotides, wherein the coding sequence for the mature polypeptides may be fused in the same reading frame to a polynucleotide sequence which aids in expression and secretion of a polypeptide from a host cell, for example, a leader sequence which functions as a secretory sequence for controlling transport of a polypeptide from the cell. The polypeptide having a leader sequence is a preprotein and may have the leader sequence cleaved by the host cell to form the mature form of the polypeptide. The polynucleotides may also encode for a proprotein which is the mature protein plus additional 5xe2x80x2 amino acid residues. A mature protein having a prosequence is a proprotein and is an inactive form of the protein. Once the prosequence is cleaved an active mature protein remains.
Thus, for example, the polynucleotide of the present invention may encode for a mature protein, or for a protein having a prosequence or for a protein having both a prosequence and a presequence (leader sequence).
The polynucleotides of the present invention may also have the coding sequence fused in frame to a marker sequence which allows for purification of the polypeptides of the present invention. The marker sequence may be a hexahistidine tag supplied by a pQE-9 vector to provide for purification of the mature polypeptides fused to the marker in the case of a bacterial host, or, for example, the marker sequence may be a hemagglutinin (HA) tag when a mammalian host, e.g. COS-7 cells, is used. The HA tag corresponds to an epitope derived from the influenza hemagglutinin protein (Wilson, I., et al., Cell, 37:767 (1984)).
The term xe2x80x9cgenexe2x80x9d means the segment of DNA involved in producing a polypeptide chain; it includes regions preceding and following the coding region (leader and trailer) as well as intervening sequences (introns) between individual coding segments (exons).
Fragments of the full length gene of the present invention may be used as a hybridization probe for a cDNA library to isolate the full length cDNA and to isolate other cDNAs which have a high sequence similarity to the gene or similar biological activity. Probes of this type preferably have at least 30 bases and may contain, for example, 50 or more bases. The probe may also be used to identify a cDNA clone corresponding to a full length transcript and a genomic clone or clones that contain the complete gene including regulatory and promotor regions, exons, and introns. An example of a screen comprises isolating the coding region of the gene by using the known DNA sequence to synthesize an oligonucleotide probe. Labeled oligonucleotides having a sequence complementary to that of the gene of the present invention are used to screen a library of human cDNA, genomic DNA or mRNA to determine which members of the library the probe hybridizes to.
The present invention further relates to polynucleotides which hybridize to the hereinabove-described sequences if there is at least 70%, preferably at least 90%, and more preferably at least 95% identity between the sequences. The present invention particularly relates to polynucleotides which hybridize under stringent conditions to the hereinabove-described polynucleotides. As herein used, the term xe2x80x9cstringent conditionsxe2x80x9d means hybridization will occur only if there is at least 95% and preferably at least 97% identity between the sequences. The polynucleotides which hybridize to the hereinabove described polynucleotides in a preferred embodiment encode polypeptides which either retain substantially the same biological function or activity as the mature polypeptide encoded by the cDNAs of FIG. 1 (SEQ ID NO:1) or the deposited cDNA(s).
Alternatively, the polynucleotide may have at least 20 bases, preferably 30 bases, and more preferably at least 50 bases which hybridize to a polynucleotide of the present invention and which has an identity thereto, as hereinabove described, and which may or may not retain activity. For example, such polynucleotides may be employed as probes for the polynucleotide of SEQ ID NO:1, for example, for recovery of the polynucleotide or as a diagnostic probe or as a PCR primer.
Thus, the present invention is directed to polynucleotides having at least a 70% identity, preferably at least 90% and more preferably at least a 95% identity to a polynucleotide which encodes the polypeptide of SEQ ID NO:2 as well as fragments thereof, which fragments have at least 30 bases and preferably at least 50 bases and to polypeptides encoded by such polynucleotides.
The deposit(s) referred to herein will be maintained under the terms of the Budapest Treaty on the International Recognition of the Deposit of Micro-organisms for purposes of Patent Procedure. These deposits are provided merely as convenience to those of skill in the art and are not an admission that a deposit is required under 35 U.S.C. xc2xa7112. The sequence of the polynucleotides contained in the deposited materials, as well as the amino acid sequence of the polypeptides encoded thereby, are incorporated herein by reference and are controlling in the event of any conflict with any description of sequences herein. A license may be required to make, use or sell the deposited materials, and no such license is hereby granted.
The present invention further relates to chemokine polypeptides which have the deduced amino acid sequences of FIG. 1 (SEQ ID No. 2) or which has the amino acid sequence encoded by the deposited cDNA, as well as fragments, analogs and derivatives of such polypeptides.
The terms xe2x80x9cfragment,xe2x80x9d xe2x80x9cderivativexe2x80x9d and xe2x80x9canalogxe2x80x9d when referring to the polypeptides of FIG. 1 (SEQ ID No. 2) or that encoded by the deposited cDNA, means polypeptides which retain essentially the same biological function or activity as such polypeptides. Thus, an analog includes a proprotein which can be activated by cleavage of the proprotein portion to produce an active mature polypeptide.
The chemokine polypeptides of the present invention may be recombinant polypeptides, natural polypeptides or a synthetic polypeptides, preferably recombinant polypeptides.
The fragment, derivative or analog of the polypeptides of FIG. 1 (SEQ ID No. 2) or that encoded by the deposited cDNA may be (i) one in which one or more of the amino acid residues are substituted with a conserved or non-conserved amino acid residue (preferably a conserved amino acid residue) and such substituted amino acid residue may or may not be one encoded by the genetic code, or (ii) one in which one or more of the amino acid residues includes a substituent group, or (iii) one in which the mature polypeptide is fused with another compound, such as a compound to increase the half-life of the polypeptide (for example, polyethylene glycol), or (iv) one in which the additional amino acids are fused to the mature polypeptide, such as a leader or secretory sequence or a sequence which is employed for purification of the mature polypeptide or a proprotein sequence. Such fragments, derivatives and analogs are deemed to be within the scope of those skilled in the art from the teachings herein.
The polypeptides and polynucleotides of the present invention are preferably provided in an isolated form, and preferably are purified to homogeneity.
The term xe2x80x9cisolatedxe2x80x9d means that the material is removed from its original environment (e.g., the natural environment if it is naturally occurring). For example, a naturally-occurring polynucleotide or polypeptide present in a living animal is not isolated, but the same polynucleotide or polypeptide, separated from some or all of the coexisting materials in the natural system, is isolated. Such polynucleotides could be part of a vector and/or such polynucleotides or polypeptides could be part of a composition, and still be isolated in that such vector or composition is not part of its natural environment.
The polypeptides of the present invention include the polypeptide of SEQ ID NO:2 (in particular the mature polypeptide) as well as polypeptides which have at least 70% similarity (preferably at least 70% identity) to the polypeptide of SEQ ID NO:2 and more preferably at least 90% similarity (more preferably at least 90% identity) to the polypeptide of SEQ ID NO:2 and still more preferably at least 95% similarity (still more preferably at least 95% identity) to the polypeptide of SEQ ID NO:2 and also include portions of such polypeptides with such portion of the polypeptide generally containing at least 30 amino acids and more preferably at least 50 amino acids.
As known in the art xe2x80x9csimilarityxe2x80x9d between two polypeptides is determined by comparing the amino acid sequence and its conserved amino acid substitutes of one polypeptide to the sequence of a second polypeptide.
Fragments or portions of the polypeptides of the present invention may be employed for producing the corresponding full-length polypeptide by peptide synthesis; therefore, the fragments may be employed as intermediates for producing the full-length polypeptides. Fragments or portions of the polynucleotides of the present invention may be used to synthesize full-length polynucleotides of the present invention.
The present invention also relates to vectors which include polynucleotides of the present invention, host cells which are genetically engineered with vectors of the invention and the production of polypeptides of the invention by recombinant techniques.
Host cells are genetically engineered (transduced or transformed or transfected) with the vectors of this invention which may be, for example, a cloning vector or an expression vector. The vector may be, for example, in the form of a plasmid, a viral particle, a phage, etc. The engineered host cells can be cultured in conventional nutrient media modified as appropriate for activating promoters, selecting transformants or amplifying the Ckxcex2-9 genes. The culture conditions, such as temperature, pH and the like, are those previously used with the host cell selected for expression, and will be apparent to the ordinarily skilled artisan.
The polynucleotides of the present invention may be employed for producing polypeptides by recombinant techniques. Thus, for example, the polynucleotide may be included in any one of a variety of expression vectors for expressing a polypeptide. Such vectors include chromosomal, nonchromosomal and synthetic DNA sequences, e.g., derivatives of SV40; bacterial plasmids; phage DNA; baculovirus; yeast plasmids; vectors derived from combinations of plasmids and phage DNA, viral DNA such as vaccinia, adenovirus, fowl pox virus, and pseudorabies. However, any other vector may be used as long as it is replicable and viable in the host.
The appropriate DNA sequence may be inserted into the vector by a variety of procedures. In general, the DNA sequence is inserted into an appropriate restriction endonuclease site(s) by procedures known in the art. Such procedures and others are deemed to be within the scope of those skilled in the art.
The DNA sequence in the expression vector is operatively linked to an appropriate expression control sequence(s) (promoter) to direct mRNA synthesis. As representative examples of such promoters, there may be mentioned: LTR or SV40 promoter, the E. coli. lac or trp, the phage lambda PL promoter and other promoters known to control expression of genes in prokaryotic or eukaryotic cells or their viruses. The expression vector also contains a ribosome binding site for translation initiation and a transcription terminator. The vector may also include appropriate sequences for amplifying expression.
In addition, the expression vectors preferably contain one or more selectable marker genes to provide a phenotypic trait for selection of transformed host cells such as dihydrofolate reductase or neomycin resistance for eukaryotic cell culture, or such as tetracycline or ampicillin resistance in E. coli.
The vector containing the appropriate DNA sequence as hereinabove described, as well as an appropriate promoter or control sequence, may be employed to transform an appropriate host to permit the host to express the protein.
As representative examples of appropriate hosts, there may be mentioned: bacterial cells, such as E. coli, Streptomyces, Salmonella typhimurium; fungal cells, such as yeast; insect cells such as Drosophila S2 and Spodoptera Sf9; animal cells such as CHO, COS or Bowes melanoma; adenoviruses; plant cells, etc. The selection of an appropriate host is deemed to be within the scope of those skilled in the art from the teachings herein.
More particularly, the present invention also includes recombinant constructs comprising one or more of the sequences as broadly described above. The constructs comprise a vector, such as a plasmid or viral vector, into which a sequence of the invention has been inserted, in a forward or reverse orientation. In a preferred aspect of this embodiment, the construct further comprises regulatory sequences, including, for example, a promoter, operably linked to the sequence. Large numbers of suitable vectors and promoters are known to those of skill in the art, and are commercially available. The following vectors are provided by way of example. Bacterial: pQE70, pQE60, pQE-9 (Qiagen), pBS, pD10, phagescript, psiX174, pBluescript SK, pBSKS, pNH8A, pNH16a, pNH18A, pNH46A (Stratagene); ptrc99a, pKK223-3, pKK233-3, pDR540, pRIT5 (Pharmacia). Eukaryotic: pWLNEO, pSV2CAT, pOG44, pXT1, pSG (Stratagene) pSVK3, pBPV, pMSG, pSVL (Pharmacia). However, any other plasmid or vector may be used as long as they are replicable and viable in the host.
Promoter regions can be selected from any desired gene using CAT (chloramphenicol transferase) vectors or other vectors with selectable markers. Two appropriate vectors are pKK232-8 and pCM7. Particular named bacterial promoters include lacI, lacZ, T3, T7, gpt, lambda PR, PL and trp. Eukaryotic promoters include CMV immediate early, HSV thymidine kinase, early and late SV40, LTRs from retrovirus, and mouse metallothionein-I. Selection of the appropriate vector and promoter is well within the level of ordinary skill in the art.
In a further embodiment, the present invention relates to host cells containing the above-described constructs. The host cell can be a higher eukaryotic cell, such as a mammalian cell, or a lower eukaryotic cell, such as a yeast cell, or the host cell can be a prokaryotic cell, such as a bacterial cell. Introduction of the construct into the host cell can be effected by calcium phosphate transfection, DEAE-Dextran mediated transfection, or electroporation (Davis, L., Dibner, M., Battey, I., Basic Methods in Molecular Biology, (1986)).
The constructs in host cells can be used in a conventional manner to produce the gene product encoded by the recombinant sequence. Alternatively, the polypeptides of the invention can be synthetically produced by conventional peptide synthesizers.
Mature proteins can be expressed in mammalian cells, yeast, bacteria, or other cells under the control of appropriate promoters. Cell-free translation systems can also be employed to produce such proteins using RNAs derived from the DNA constructs of the present invention. Appropriate cloning and expression vectors for use with prokaryotic and eukaryotic hosts are described by Sambrook, et al., Molecular Cloning: A Laboratory Manual, Second Edition, Cold Spring Harbor, N.Y., (1989), the disclosure of which is hereby incorporated by reference.
Transcription of the DNA encoding the polypeptides of the present invention by higher eukaryotes is increased by inserting an enhancer sequence into the vector. Enhancers are cis-acting elements of DNA, usually about from 10 to 300 bp that act on a promoter to increase its transcription. Examples including the SV40 enhancer on the late side of the replication origin bp 100 to 270, a cytomegalovirus early promoter enhancer, the polyoma enhancer on the late side of the replication origin, and adenovirus enhancers.
Generally, recombinant expression vectors will include origins of replication and selectable markers permitting transformation of the host cell, e.g., the ampicillin resistance gene of E. coli and S. cerevisiae TRP1 gene, and a promoter derived from a highly-expressed gene to direct transcription of a downstream structural sequence. Such promoters can be derived from operons encoding glycolytic enzymes such as 3-phosphoglycerate kinase (PGK), xcex1-factor, acid phosphatase, or heat shock proteins, among others. The heterologous structural sequence is assembled in appropriate phase with translation initiation and termination sequences, and preferably, a leader sequence capable of directing secretion of translated protein into the periplasmic space or extracellular medium. Optionally, the heterologous sequence can encode a fusion protein including an N-terminal identification peptide imparting desired characteristics, e.g., stabilization or simplified purification of expressed recombinant product.
Useful expression vectors for bacterial use are constructed by inserting a structural DNA sequence encoding a desired protein together with suitable translation initiation and termination signals in operable reading phase with a functional promoter. The vector will comprise one or more phenotypic selectable markers and an origin of replication to ensure maintenance of the vector and to, if desirable, provide amplification within the host. Suitable prokaryotic hosts for transformation include E. coli, Bacillus subtilis, Salmonella typhimurium and various species within the genera Pseudomonas, Streptomyces, and Staphylococcus, although others may also be employed as a matter of choice.
As a representative but nonlimiting example, useful expression vectors for bacterial use can comprise a selectable marker and bacterial origin of replication derived from commercially available plasmids comprising genetic elements of the well known cloning vector pBR322 (ATCC 37017). Such commercial vectors include, for example, pKK223-3 (Pharmacia Fine Chemicals, Uppsala, Sweden) and pGEM1 (Promega Biotec, Madison, Wis., USA). These pBR322 xe2x80x9cbackbonexe2x80x9d sections are combined with an appropriate promoter and the structural sequence to be expressed.
Following transformation of a suitable host strain and growth of the host strain to an appropriate cell density, the selected promoter is induced by appropriate means (e.g., temperature shift or chemical induction) and cells are cultured for an additional period.
Cells are typically harvested by centrifugation, disrupted by physical or chemical means, and the resulting crude extract retained for further purification.
Microbial cells employed in expression of proteins can be disrupted by any convenient method, including freeze-thaw cycling, sonication, mechanical disruption, or use of cell lysing agents, such methods are well know to those skilled in the art.
Various mammalian cell culture systems can also be employed to express recombinant protein. Examples of mammalian expression systems include the COS-7 lines of monkey kidney fibroblasts, described by Gluzman, Cell, 23:175 (1981), and other cell lines capable of expressing a compatible vector, for example, the C127, 3T3, CHO, HeLa and BHK cell lines. Mammalian expression vectors will comprise an origin of replication, a suitable promoter and enhancer, and also any necessary ribosome binding sites, polyadenylation site, splice donor and acceptor sites, transcriptional termination sequences, and 5xe2x80x2 flanking nontranscribed sequences. DNA sequences derived from the SV40 splice, and polyadenylation sites may be used to provide the required nontranscribed genetic elements.
The Ckxcex2-9 polypeptides can be recovered and purified from recombinant cell cultures by methods including ammonium sulfate or ethanol precipitation, acid extraction, anion or cation exchange chromatography, phosphocellulose chromatography, hydrophobic interaction chromatography, affinity chromatography, hydroxylapatite chromatography and lectin chromatography. Protein refolding steps can be used, as necessary, in completing configuration of the mature protein. Finally, high performance liquid chromatography (HPLC) can be employed for final purification steps.
The polypeptides of the present invention may be a naturally purified product, or a product of chemical synthetic procedures, or produced by recombinant techniques from a prokaryotic or eukaryotic host (for example, by bacterial, yeast, higher plant, insect and mammalian cells in culture). Depending upon the host employed in a recombinant production procedure, the polypeptides of the present invention may be glycosylated or may be non-glycosylated. Polypeptides of the invention may also include an initial methionine amino acid residue.
The Ckxcex2-9 polypeptides may be employed to inhibit bone marrow stem cell colony formation as adjunct protective treatment during cancer chemotherapy and for leukemia.
The chemokine polypeptides may also be used to inhibit epidermal keratinocyte proliferation for treatment of psoriasis, which is characterized by keratinocyte hyper-proliferation.
The chemokine polypeptides may also be used to treat solid tumors by stimulating the invasion and activation of host defense cells, e.g., cytotoxic T cells and macrophages. They may also be used to enhance host defenses against resistant chronic infections, for example, mycobacterial infections via the attraction and activation of microbicidal leukocytes.
The chemokine polypeptides may also be used to treat auto-immune disease and lymphocytic leukemia by inhibiting T cell proliferation by the inhibition of IL2 biosynthesis.
Ckxcex2-9 may also be used in wound healing, both via the recruitment of debris clearing and connective tissue promoting inflammatory cells and also via its control of excessive TGFxcex2-mediated fibrosis. In this same manner, Ckxcex2-9 may also be used to treat other fibrotic disorders, including liver cirrhosis, osteoarthritis and pulmonary fibrosis.
The chemokine polypeptides also increase the presence of eosinophils which have the distinctive function of killing the larvae of parasites that invade tissues, as in schistosomiasis, trichinosis and ascariasis.
They may also be used to regulate hematopoiesis, by regulating the activation and differentiation of various hematopoietic progenitor cells, for example, to release mature leukocytes from the bone marrow following chemotherapy.
The polynucleotides and polypeptides encoded by such polynucleotides may also be utilized for in vitro purposes related to scientific research, synthesis of DNA and manufacture of DNA vectors and for designing therapeutics and diagnostics for the treatment of human disease.
Fragments of the full length Ckxcex2-9 genes may be used as a hybridization probe for a cDNA library to isolate the full length gene and to isolate other genes which have a high sequence similarity to the gene or similar biological activity. Probes of this type can be, for example, between 20 and 2000 bases. Preferably, however, the probes have between 30 and 50 base pairs. The probe may also be used to identify a cDNA clone corresponding to a full length transcript and a genomic clone or clones that contain the complete genes including regulatory and promotor regions, exons, and introns. An example of a screen comprises isolating the coding region of the genes by using the known DNA sequence to synthesize an oligonucleotide probe. Labeled oligonucleotides having a sequence complementary to that of the genes of the present invention are used to screen a library of human cDNA, genomic DNA or mRNA to determine which members of the library the probe hybridizes to.
This invention is also related to the use of the Ckxcex2-9 gene as part of a diagnostic assay for detecting diseases or susceptibility to diseases related to the presence of mutations in the Ckxcex2-9 nucleic acid sequences. Such diseases are related to under-expression of the chemokine polypeptides, for example, tumors and cancers.
Individuals carrying mutations in the Ckxcex2-9 gene may be detected at the DNA level by a variety of techniques. Nucleic acids for diagnosis may be obtained from a patient""s cells, such as from blood, urine, saliva, tissue biopsy and autopsy material. The genomic DNA may be used directly for detection or may be amplified enzymatically by using PCR (Saiki et al., Nature, 324:163-166 (1986)) prior to analysis. RNA or cDNA may also be used for the same purpose. As an example, PCR primers complementary to the nucleic acid encoding Ckxcex2-9 can be used to identify and analyze Ckxcex2-9 mutations. For example, deletions and insertions can be detected by a change in size of the amplified product in comparison to the normal genotype. Point mutations can be identified by hybridizing amplified DNA to radiolabeled Ckxcex2-9 RNA or alternatively, radiolabeled Ckxcex2-9 antisense DNA sequences. Perfectly matched sequences can be distinguished from mismatched duplexes by RNase A digestion or by differences in melting temperatures.
Genetic testing based on DNA sequence differences may be achieved by detection of alteration in electrophoretic mobility of DNA fragments in gels with or without denaturing agents. Small sequence deletions and insertions can be visualized by high resolution gel electrophoresis. DNA fragments of different sequences may be distinguished on denaturing formamide gradient gels in which the mobilities of different DNA fragments are retarded in the gel at different positions according to their specific melting or partial melting temperatures (see, e.g., Myers et al., Science, 230:1242 (1985)).
Sequence changes at specific locations may also be revealed by nuclease protection assays, such as RNase and S1 protection or the chemical cleavage method (e.g., Cotton et al., PNAS, USA, 85:4397-4401 (1985)).
Thus, the detection of a specific DNA sequence may be achieved by methods such as hybridization, RNase protection, chemical cleavage, direct DNA sequencing or the use of restriction enzymes, (e.g., Restriction Fragment Length Polymorphisms (RFLP)) and Southern blotting of genomic DNA.
In addition to more conventional gel-electrophoresis and DNA sequencing, mutations can also be detected by in situ analysis.
The present invention also relates to a diagnostic assay for detecting altered levels of Ckxcex2-9 protein in various tissues since an over-expression of the proteins compared to normal control tissue samples may detect the presence of a disease or susceptibility to a disease, for example, a tumor. Assays used to detect levels of Ckxcex2-9 protein in a sample derived from a host are well-known to those of skill in the art and include radioimmunoassays, competitive-binding assays, Western Blot analysis, ELISA assays and xe2x80x9csandwichxe2x80x9d assay. An ELISA assay (Coligan, et al., Current Protocols in Immunology, 1(2), Chapter 6, (1991)) initially comprises preparing an antibody specific to the Ckxcex2-9 antigen, preferably a monoclonal antibody. In addition a reporter antibody is prepared against the monoclonal antibody. To the reporter antibody is attached a detectable reagent such as radioactivity, fluorescence or, in this example, a horseradish peroxidase enzyme. A sample is removed from a host and incubated on a solid support, e.g. a polystyrene dish, that binds the proteins in the sample. Any free protein binding sites on the dish are then covered by incubating with a non-specific protein like bovine serum albumin. Next, the monoclonal antibody is incubated in the dish during which time the monoclonal antibodies attach to any Ckxcex2-9 proteins attached to the polystyrene dish. All unbound monoclonal antibody is washed out with buffer. The reporter antibody linked to horseradish peroxidase is now placed in the dish resulting in binding of the reporter antibody to any monoclonal antibody bound to Ckxcex2-9. Unattached reporter antibody is then washed out. Peroxidase substrates are then added to the dish and the amount of color developed in a given time period is a measurement of the amount of Ckxcex2-9 protein present in a given volume of patient sample when compared against a standard curve.
A competition assay may be employed wherein antibodies specific to Ckxcex2-9 are attached to a solid support and labeled Ckxcex2-9 and a sample derived from the host are passed over the solid support and the amount of label detected, for example by liquid scintillation chromatography, can be correlated to a quantity of Ckxcex2-9 in the sample.
A xe2x80x9csandwichxe2x80x9d assay is similar to an ELISA assay. In a xe2x80x9csandwichxe2x80x9d assay Ckxcex2-9 is passed over a solid support and binds to antibody attached to a solid support. A second antibody is then bound to the Ckxcex2-9. A third antibody which is labeled and specific to the second antibody is then passed over the solid support and binds to the second antibody and an amount can then be quantified.
This invention provides a method for identification of the receptors for Ckxcex2-9 polypeptides. The gene encoding the receptor can be identified by numerous methods known to those of skill in the art, for example, ligand panning and FACS sorting (Coligan, et al., Current Protocols in Immun., 1(2), Chapter 5, (1991)). Preferably, expression cloning is employed wherein polyadenylated RNA is prepared from a cell responsive to the polypeptides, and a cDNA library created from this RNA is divided into pools and used to transfect COS cells or other cells that are not responsive to the polypeptides. Transfected cells which are grown on glass slides are exposed to the labeled polypeptides. The polypeptides can be labeled by a variety of means including iodination or inclusion of a recognition site for a site-specific protein kinase. Following fixation and incubation, the slides are subjected to autoradiographic analysis. Positive pools are identified and sub-pools are prepared and re-transfected using an iterative sub-pooling and rescreening process, eventually yielding a single clones that encodes the putative receptor.
As an alternative approach for receptor identification, the labeled polypeptides can be photo-affinity linked with cell membrane or extract preparations that express the receptor molecule. Cross-linked material is resolved by PAGE analysis and exposed to x-ray film. The labeled complex containing the receptors of the polypeptides can be excised, resolved into peptide fragments, and subjected to protein micro-sequencing. The amino acid sequence obtained from micro-sequencing would be used to design a set of degenerate oligonucleotide probes to screen a cDNA library to identify the genes encoding the putative receptors.
This invention provides a method of screening compounds to identify agonists and antagonists to the Ckxcex2-9 polypeptides of the present invention. An agonist is a compound which has similar biological functions of the polypeptides, while antagonists block such functions. Chemotaxis may be assayed by placing cells, which are chemo-attracted by either of the polypeptides of the present invention, on top of a filter with pores of sufficient diameter to admit the cells (about 5 xcexcm). Solutions of potential agonists are placed in the bottom of the chamber with an appropriate control medium in the upper compartment, and thus a concentration gradient of the agonist is measured by counting cells that migrate into or through the porous membrane over time.
When assaying for antagonists, the polypeptides of the present invention are placed in the bottom chamber and the potential antagonist is added to determine if chemotaxis of the cells is prevented.
Alternatively, a mammalian cell or membrane preparation expressing the receptors of the polypeptides would be incubated with a labeled Ckxcex2-9 polypeptide, eg. radioactivity, in the presence of the compound. The ability of the compound to block this interaction could then be measured. When assaying for agonists in this fashion, the chemokines would be absent and the ability of the agonist itself to interact with the receptor could be measured.
Examples of potential Ckxcex2-9 antagonists include antibodies, or in some cases, oligonucleotides, which bind to the polypeptides. Another example of a potential antagonist is a negative dominant mutant of the polypeptides. Negative dominant mutants are polypeptides which bind to the receptor of the wild-type polypeptide, but fail to retain biological activity.
Antisense constructs prepared using antisense technology are also potential antagonists. Antisense technology can be used to control gene expression through triple-helix formation or antisense DNA or RNA, both of which methods are based on binding of a polynucleotide to DNA or RNA. For example, the 5xe2x80x2 coding portion of the polynucleotide sequence, which encodes for the mature polypeptides of the present invention, is used to design an antisense RNA oligonucleotide of from about 10 to 40 base pairs in length. A DNA oligonucleotide is designed to be complementary to a region of the gene involved in transcription (triple-helix, see Lee et al., Nucl. Acids Res., 6:3073 (1979); Cooney et al, Science, 241:456 (1988); and Dervan et al., Science, 251:1360 (1991)), thereby preventing transcription and the production of the chemokine polypeptides. The antisense RNA oligonucleotide hybridizes to the mRNA in vivo and blocks translation of the mRNA molecule into the polypeptides (antisensexe2x80x94Okano, J. Neurochem., 56:560 (1991); Oligodeoxynucleotides as Antisense Inhibitors of Gene Expression, CRC Press, Boca Raton, Fla. (1988)). The oligonucleotides described above can also be delivered to cells such that the antisense RNA or DNA may be expressed in vivo to inhibit production of Ckxcex2-9.
Another potential Ckxcex2-9 antagonist is a peptide derivative of the polypeptides which are naturally or synthetically modified analogs of the polypeptides that have lost biological function yet still recognize and bind to the receptors of the polypeptides to thereby effectively block the receptors. Examples of peptide derivatives include, but are not limited to, small peptides or peptide-like molecules.
The antagonists may be employed to inhibit the chemotaxis and activation of macrophages and their precursors, and of neutrophils, basophils, B lymphocytes and some T cell subsets, e.g., activated and CD8 cytotoxic T cells and natural killer cells, in auto-immune and chronic inflammatory and infective diseases. Examples of auto-immune diseases include rheumatoid arthritis, multiple sclerosis, and insulin-dependent diabetes. Some infectious diseases include silicosis, sarcoidosis, idiopathic pulmonary fibrosis by preventing the recruitment and activation of mononuclear phagocytes, idiopathic hyper-eosinophilic syndrome by preventing eosinophil production and migration, endotoxic shock by preventing the migration of macrophages and their production of the chemokine polypeptides of the present invention.
The antagonists may also be employed for treating atherosclerosis, by preventing monocyte infiltration in the artery wall.
The antagonists may also be employed to treat histamine-mediated allergic reactions and immunological disorders including late phase allergic reactions, chronic urticaria, and atopic dermatitis by inhibiting chemokine-induced mast cell and basophil degranulation and release of histamine. IgE-mediated allergic reactions such as allergic asthma, rhinitis, and eczema may also be treated.
The antagonists may also be employed to treat chronic and acute inflammation by preventing the attraction of monocytes to a wound area. They may also be employed to regulate normal pulmonary macrophage populations, since acute and chronic inflammatory pulmonary diseases are associated with sequestration of mononuclear phagocytes in the lung.
Antagonists may also be employed to treat rheumatoid arthritis by preventing the attraction of monocytes into synovial fluid in the joints of patients. Monocyte influx and activation plays a significant role in the pathogenesis of both degenerative and inflammatory arthropathies.
The antagonists may be employed to interfere with the deleterious cascades attributed primarily to IL-1 and TNF, which prevents the biosynthesis of other inflammatory cytokines. In this way, the antagonists may be employed to prevent inflammation. The antagonists may also be employed to inhibit prostaglandin-independent fever induced by chemokines.
The antagonists may also be employed to treat cases of bone marrow failure, for example, aplastic anemia and myelodysplastic syndrome.
The antagonists may also be used to treat asthma and allergy by preventing eosinophil accumulation in the lung.
The antagonists may also be employed to treat subepithelial basement membrane fibrosis which is a prominent feature of the asthmatic lung.
The antagonists may be employed in a composition with a pharmaceutically acceptable carrier, e.g., as hereinafter described.
The Ckxcex2-9 polypeptides and agonists and antagonists may be employed in combination with a suitable pharmaceutical carrier. Such compositions comprise a therapeutically effective amount of the polypeptide, and a pharmaceutically acceptable carrier or excipient. Such a carrier includes but is not limited to saline, buffered saline, dextrose, water, glycerol, ethanol, and combinations thereof. The formulation should suit the mode of administration.
The invention also provides a pharmaceutical pack or kit comprising one or more containers filled with one or more of the ingredients of the pharmaceutical compositions of the invention. Associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use or sale for human administration. In addition, the polypeptides and agonists and antagonists may be employed in conjunction with other therapeutic compounds.
The pharmaceutical compositions may be administered in a convenient manner such as by the topical, intravenous, intraperitoneal, intramuscular, intratumor, subcutaneous, intranasal or intradermal routes. The pharmaceutical compositions are administered in an amount which is effective for treating and/or prophylaxis of the specific indication. In general, the polypeptides will be administered in an amount of at least about 10 xcexcg/kg body weight and in most cases they will be administered in an amount not in excess of about 8 mg/Kg body weight per day. In most cases, the dosage is from about 10 xcexcg/kg to about 1 mg/kg body weight daily, taking into account the routes of administration, symptoms, etc.
The Ckxcex2-9 polypeptides, and agonists or antagonists which are polypeptides, may be employed in accordance with the present invention by expression of such polypeptides in vivo, which is often referred to as xe2x80x9cgene therapy.xe2x80x9d
Thus, for example, cells from a patient may be engineered with a polynucleotide (DNA or RNA) encoding a polypeptide ex vivo, with the engineered cells then being provided to a patient to be treated with the polypeptide. Such methods are well-known in the art. For example, cells may be engineered by procedures known in the art by use of a retroviral particle containing RNA encoding a polypeptide of the present invention.
Similarly, cells may be engineered in vivo for expression of a polypeptide in vivo by, for example, procedures known in the art. As known in the art, a producer cell for producing a retroviral particle containing RNA encoding the polypeptide of the present invention may be administered to a patient for engineering cells in vivo and expression of the polypeptide in vivo. These and other methods for administering a polypeptide of the present invention by such method should be apparent to those skilled in the art from the teachings of the present invention. For example, the expression vehicle for engineering cells may be other than a retrovirus, for example, an adenovirus which may be used to engineer cells in vivo after combination with a suitable delivery vehicle.
The sequences of the present invention are also valuable for chromosome identification. The sequence is specifically targeted to and can hybridize with a particular location on an individual human chromosome. Moreover, there is a current need for identifying particular sites on the chromosome. Few chromosome marking reagents based on actual sequence data (repeat polymorphisms) are presently available for marking chromosomal location. The mapping of DNAs to chromosomes according to the present invention is an important first step in correlating those sequences with genes associated with disease.
Briefly, sequences can be mapped to chromosomes by preparing PCR primers (preferably 15-25 bp) from the cDNA. Computer analysis of the 3xe2x80x2 untranslated region is used to rapidly select primers that do not span more than one exon in the genomic DNA, thus complicating the amplification process. These primers are then used for PCR screening of somatic cell hybrids containing individual human chromosomes. Only those hybrids containing the human gene corresponding to the primer will yield an amplified fragment.
PCR mapping of somatic cell hybrids is a rapid procedure for assigning a particular DNA to a particular chromosome. Using the present invention with the same oligonucleotide primers, sublocalization can be achieved with panels of fragments from specific chromosomes or pools of large genomic clones in an analogous manner. Other mapping strategies that can similarly be used to map to its chromosome include in situ hybridization, prescreening with labeled flow-sorted chromosomes and preselection by hybridization to construct chromosome specific-cDNA libraries.
Fluorescence in situ hybridization (FISH) of a cDNA clones to a metaphase chromosomal spread can be used to provide a precise chromosomal location in one step. This technique can be used with cDNA as short as 50 or 60 bases. For a review of this technique, see Verma et al., Human Chromosomes: a Manual of Basic Techniques, Pergamon Press, New York (1988).
Once a sequence has been mapped to a precise chromosomal location, the physical position of the sequence on the chromosome can be correlated with genetic map data. Such data are found, for example, in V. McKusick, Mendelian Inheritance in Man (available on line through Johns Hopkins University Welch Medical Library). The relationship between genes and diseases that have been mapped to the same chromosomal region are then identified through linkage analysis (coinheritance of physically adjacent genes).
Next, it is necessary to determine the differences in the cDNA or genomic sequence between affected and unaffected individuals. If a mutation is observed in some or all of the affected individuals but not in any normal individuals, then the mutation is likely to be the causative agent of the disease.
With current resolution of physical mapping and genetic mapping techniques, a cDNA precisely localized to a chromosomal region associated with the disease could be one of between 50 and 500 potential causative genes. (This assumes 1 megabase mapping resolution and one gene per 20 kb).
The polypeptides, their fragments or other derivatives, or analogs thereof, or cells expressing them can be used as an immunogen to produce antibodies thereto. These antibodies can be, for example, polyclonal or monoclonal antibodies. The present invention also includes chimeric, single chain, and humanized antibodies, as well as Fab fragments, or the product of an Fab expression library. Various procedures known in the art may be used for the production of such antibodies and fragments.
Antibodies generated against the polypeptides corresponding to a sequence of the present invention can be obtained by direct injection of the polypeptides into an animal or by administering the polypeptides to an animal, preferably a nonhuman. The antibody so obtained will then bind the polypeptides itself. In this manner, even a sequence encoding only a fragment of the polypeptides can be used to generate antibodies binding the whole native polypeptides. Such antibodies can then be used to isolate the polypeptide from tissue expressing that polypeptide.
For preparation of monoclonal antibodies, any technique which provides antibodies produced by continuous cell line cultures can be used. Examples include the hybridoma technique (Kohler and Milstein, 1975, Nature, 256:495-497), the trioma technique, the human B-cell hybridoma technique (Kozbor et al., 1983, Immunology Today 4:72), and the EBV-hybridoma technique to produce human monoclonal antibodies (Cole, et al., 1985, in Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, Inc., pp. 77-96).
Techniques described for the production of single chain antibodies (U.S. Pat. No. 4,946,778) can be adapted to produce single chain antibodies to immunogenic polypeptide products of this invention. Also, transgenic mice may be used to express humanized antibodies to immunogenic polypeptide products of this invention.
The present invention will be further described with reference to the following examples; however, it is to be understood that the present invention is not limited to such examples. All parts or amounts, unless otherwise specified, are by weight.
In order to facilitate understanding of the following examples certain frequently occurring methods and/or terms will be described.
xe2x80x9cPlasmidsxe2x80x9d are designated by a lower case p preceded and/or followed by capital letters and/or numbers. The starting plasmids herein are either commercially available, publicly available on an unrestricted basis, or can be constructed from available plasmids in accord with published procedures. In addition, equivalent plasmids to those described are known in the art and will be apparent to the ordinarily skilled artisan.
xe2x80x9cDigestionxe2x80x9d of DNA refers to catalytic cleavage of the DNA with a restriction enzyme that acts only at certain sequences in the DNA. The various restriction enzymes used herein are commercially available and their reaction conditions, cofactors and other requirements were used as would be known to the ordinarily skilled artisan. For analytical purposes, typically 1 xcexcg of plasmid or DNA fragment is used with about 2 units of enzyme in about 20 xcexcl of buffer solution. For the purpose of isolating DNA fragments for plasmid construction, typically 5 to 50 xcexcg of DNA are digested with 20 to 250 units of enzyme in a larger volume. Appropriate buffers and substrate amounts for particular restriction enzymes are specified by the manufacturer. Incubation times of about 1 hour at 37xc2x0 C. are ordinarily used, but may vary in accordance with the supplier""s instructions. After digestion the reaction is electrophoresed directly on a polyacrylamide gel to isolate the desired fragment.
Size separation of the cleaved fragments is performed using 8 percent polyacrylamide gel described by Goeddel, D. et al., Nucleic Acids Res., 8:4057 (1980).
xe2x80x9cOligonucleotidesxe2x80x9d refers to either a single stranded polydeoxynucleotide or two complementary polydeoxynucleotide strands which may be chemically synthesized. Such synthetic oligonucleotides have no 5xe2x80x2 phosphate and thus will not ligate to another oligonucleotide without adding a phosphate with an ATP in the presence of a kinase. A synthetic oligonucleotide will ligate to a fragment that has not been dephosphorylated.
xe2x80x9cLigationxe2x80x9d refers to the process of forming phosphodiester bonds between two double stranded nucleic acid fragments (Maniatis, T., et al., Id., p. 146). Unless otherwise provided, ligation may be accomplished using known buffers and conditions with 10 units to T4 DNA ligase (xe2x80x9cligasexe2x80x9d) per 0.5 xcexcg of approximately equimolar amounts of the DNA fragments to be ligated.
Unless otherwise stated, transformation was performed as described in the method of Graham, F. and Van der Eb, A., Virology, 52:456-457 (1973).


A computer-implemented method, system and computer program product for analyzing test result failures using artificial intelligence models. A first machine learning model is trained to differentiate between a bug failure and a test failure within the test failures based on the failure attributes and historical failures. The failure type for each failed test in test failure groups is then determined using the first machine learning model. The failed tests in the test failure groups are then clustered into a set of clusters according to the failure attributes and the determined failure type for each failed test. A root cause failure for each cluster is identified based on the set of clusters and the failure attributes. The root cause of an unclassified failure is predicted using a second machine learning model trained to predict a root cause of the unclassified failure based on identifying the root cause failure for each cluster.

In software testing, test automation is the use of software, such as in a test suite (referred to herein as the "automated test suite"), separate from the software being tested to control the execution of tests and the comparison of actual outcomes with predicted outcomes. Test automation can automate some repetitive but necessary tasks in a formalized testing process already in place, or perform additional testing that would be difficult to do manually. Test automation is critical for continuous delivery and continuous testing.

This patent is subject to a terminal disclaimer.

Analyzing test result failures using artificial intelligence models

International Business Machines Corporation